What's up with automatic slack adjusters?

Correct, if they arent adjusting on their own, they are either installed wrong or worn out. (Or your brakes are worn out)

 

The number one reason for auto adjusters not working is the driver. You got to build air up with brakes released and smash the brake pedal down to the flood and hold it there for 30 seconds. Do this five times with full air pressure once a week. This is how they ratchet up and adjust. If they don't adjust then they are defective. Also self adjusting them all time makes them go bad cause wear the teeth off backing them off.

 

I’ve never had an issue with mine, I just drive the truck and they auto adjust. No stomping the brake pedal down or anything else. I do keep them greased.

 

Keeping them greased and like mentioned before hard brake applications help. some slacks are angle adjusting others are stroke adjusting. If they do not stay in adjustment then yes you have other issues going on in the foundation brakes.
bad s cam bushings worn out s cams or bad slacks.
I have a hard time keeping mine in adjustment if I don’t do the stomp the pedal to the floor a couple times while stationary. I do such light brake applications they would never adjust up under normal use.

 

I can always hear mine adjust. One rule of thumb I go by, while waiting in line to go across a DOT scale, while you're behind another truck sitting still, mat the brake pedal and listen for the clunk. Move up with the flow of traffic, and as soon as you stop again, mat the brake again. That way, if you're pulled in for an inspection... they're adjusted as much as they can be.

 

If you're easy on the brakes most times then they don't ratchet over enough. Especially if you keep them greased up. I try to do several hard emergency applications every so often at red lights to keep them moving over.

 

Also if you ever do the pump down airbrake test. It adjusts them. So either the 5-85-5 or pump down will do it.

 

They wear out, we replace a lot of them because of wear, it isn’t just drivers not going through the adjustment process.

they are also made to adjust while using the service brakes when driving: bendix says this.